Amino Acids and Proteins: Characteristics and Structure

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Questions and Answers

What is the three-dimensional structure of a multisubunit protein called?

Quaternary structure (correct)

Primary structure

Tertiary structure

Secondary structure

Which of the following denaturing agents can lead to protein precipitation?

Hydrophobic interactions

Heat and pH (correct)

Covalent disulfide bonds

Hydrogen bonds and salt bridges

What is the process of refolding an unfolded (denatured) protein to restore its native structure and function called?

Renaturation (correct)

Aggregation

Polymerization

Precipitation

Which type of proteins consist of two separate polypeptide chains or subunits?

Dimeric proteins Signup and view all the answers

What percentage of the body weight consists of proteins?

50% Signup and view all the answers

The 3D structure of a protein is related to its function. True or False?

True Signup and view all the answers

What are proteins formed from?

Amino acids Signup and view all the answers

Where does the amino acid sequence of a protein depend on?

Genetic information encoded in DNA Signup and view all the answers

Which group of proteins is characterized by a fibrous shape?

Conjugated proteins Signup and view all the answers

Where do polar amino acids tend to be located in a protein's structure?

In contact with water Signup and view all the answers

How many main classes are common amino acids divided into based on their properties?

Five Signup and view all the answers

What do nonpolar amino acids constitute in the protein's structure?

Hydrophobic region Signup and view all the answers

Which molecular components do proteins serve as?

Amino acids and carbohydrates Signup and view all the answers

What is the role of proteins in the body?

Catalyzing biochemical reactions Signup and view all the answers

Which type of amino acid has an asymmetric carbon?

Uncharged Signup and view all the answers

What term describes compounds that are non superposable mirror images of each other?

Stereoisomers Signup and view all the answers

Which functional groups in amino acids function as weak acids and bases?

Amino and carboxyl groups Signup and view all the answers

What type of bond is formed by removal of the elements of water between two amino acid molecules?

Peptide bond Signup and view all the answers

What is the primary structure of a protein?

The sequence of amino acids that form the protein chain from the first amino acid to the last one Signup and view all the answers

What is the secondary structure that involves a tightly wound helical conformation of a polypeptide chain?

α-helix Signup and view all the answers

What stabilizes the structure of α-helix in proteins?

Hydrogen bonds Signup and view all the answers

What is the secondary structure that has an extended conformation of polypeptide chains arranged into a zigzag?

β-pleated sheet Signup and view all the answers

In which type of β-pleated sheet do the polypeptide chains run in the same direction?

Parallel β sheet Signup and view all the answers

What type of turn involves four amino acid residues and is important in compacted globular proteins?

Beta turn Signup and view all the answers

What does the tertiary structure of a protein reflect?

The overall shape of the molecule Signup and view all the answers

What is the characteristic of a zwitterion or dipolar ion?

Able to donate and accept protons Signup and view all the answers

Study Notes

Protein Structure and Function

The three-dimensional structure of a multisubunit protein is called a quaternary structure.
Denaturing agents like trichloroacetic acid, phenol, and acetone can lead to protein precipitation.
The process of refolding an unfolded (denatured) protein to restore its native structure and function is called renaturation.

Protein Composition and Formation

Proteins consist of two separate polypeptide chains or subunits.
About 15-20% of the body weight consists of proteins.
Proteins are formed from amino acids.
The amino acid sequence of a protein depends on the sequence of nucleotides in the gene that encodes it.

Amino Acid Properties

Amino acids are divided into two main classes based on their properties: polar and nonpolar.
Nonpolar amino acids constitute the hydrophobic core of the protein's structure.
Polar amino acids tend to be located on the surface of a protein's structure.

Functional Groups and Bonds

The amino and carboxyl functional groups in amino acids function as weak acids and bases.
A peptide bond is formed by removal of the elements of water between two amino acid molecules.

Protein Structure Hierarchy

The primary structure of a protein is the sequence of amino acids.
The secondary structure that involves a tightly wound helical conformation of a polypeptide chain is an α-helix.
Hydrogen bonds stabilize the structure of an α-helix in proteins.
The secondary structure that has an extended conformation of polypeptide chains arranged into a zigzag is a β-pleated sheet.
In a parallel β-pleated sheet, the polypeptide chains run in the same direction.
A β-turn involves four amino acid residues and is important in compacted globular proteins.
The tertiary structure of a protein reflects the overall 3D shape of a polypeptide chain.

Chirality and Ions

An asymmetric carbon atom is found in amino acids with chiral centers.
Enantiomers are compounds that are non-superposable mirror images of each other.
Zwitterions or dipolar ions have both positive and negative charges.

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Description

Test your knowledge about the characteristics, structure, and classification of amino acids and proteins including peptide bonds, structural protein levels, 3D protein structure, and the relationship between structure and function. Explore the linear polymer formation of proteins from amino acids and their dependence on genetic information encoded in DNA.